Full charge should take 6 hours.
It seems some chargers charge at lower speed for an unknown reason. If you can't get full charge even with 7-8 hours then I would suggest trying another charger.
If you are charging only you can test with 1A or more
If you are charging and system is on you need 1.5A or more

1) The other day I plugged the charger while the system was on, and it turned off at the time it started charging with a little cracking sound. It is normal to have that shutdown when plugging the charger? I think it only happened one time.

2)While using the proper charger, the RetroStone is suppossed to be able tu run fine and charge at the same time? This is only to know if it's ok to play while you are charging the unit.

1) The other day I plugged the charger while the system was on, and it turned off at the time it started charging with a little cracking sound. It is normal to have that shutdown when plugging the charger? I think it only happened one time.

2)While using the proper charger, the RetroStone is suppossed to be able tu run fine and charge at the same time? This is only to know if it's ok to play while you are charging the unit.

Cheers!

Hello there.
1) Yes this happened to me too, is better plug the charger when the device is off and after turn on
2)Yes i scraped the roms with the charger plugged into the device. I think isn't good play with the device during the charge this might broke the battery. If you wanna play with the retrostone with the charger plugged is better remove the battery (i didin't tested it i haven't my retrostone here i waiting for an replacdment )